• Journal of the Society of Naval Architects of Korea
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• v.49 no.5
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• pp.367-375
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• 2012

In this study, hull form of main vessel of Korean large purse seiner fishing industry is developed for the improvement of resistance performance as well as for the satisfaction to the Standard of Fishing Convention, ILO. Through the modification of reference hull form parameters and local characteristics, the hull form development is carried out. The optimum hull form parameters are searched by Sequential Quadratic Programing(SQP) method with the power estimation method of Holtrop & Mannen. To minimize the wave resistance, bulbous bow parameters are determined by the bulbous bow design method of Alvarino. The plasmatic curve is redesigned from that of the reference hull by using Lackenby method. The resistance performances of the reference and designed hull forms are estimated by using numerical simulation method. Also, the judgment of seakeeping ability and the estimation of intact stability for the designed hull form is carried out. As a result, the optimum hull form is proposed. To verify the improvement of resistance performance, model tests are carried out in towing tank. The results show that the resistance of the designed hull form is about 14% smaller than that of the reference hull from at design speed. A new hull form proposed in this study can contribute to the development of the main vessel hull form of Korean large purse seiner fishing system.

• The KSFM Journal of Fluid Machinery
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• v.15 no.4
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• pp.19-26
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• 2012

In this paper, a parametric study on ribs which are installed in an equilateral triangular internal cooling channel is presented. The numerical analysis of the flow structure and heat transfer characteristics is performed using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. The numerical results are obtained at Reynolds number, 20,000. The parametric study is performed for the parameters, the angle of a rib, rib pitch-to-hydraulic diameter ratio, rib width-to-hydraulic diameter ratio, and rib height-to-hydraulic diameter ratio. The computational results are validated with the experimental data for area-averaged Nusselt number.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1662-1668
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• 2011

Steric and electronic parameters of 4'-substituents play significant roles in steering the conformation of nucleoside analogues. In order to investigate the relationship of 4'-substituent with antiviral enhancement, novel 4'-phenyl-5'-norcarbocyclic adenosine phosphonic acid analogues were racemically synthesized via de novo acyclic stereoselective route from propionaldehyde 5. The phenyl substituted cyclopentenols 15a and 15b as key intermediates were successfully constructed via reiterative carbonyl addition of Grignard reagents and ring-closing metathesis of corresponding divinyl 14. The synthesized nucleoside phosphonic acids analogues 19, 20, 21, and 23 were subjected to antiviral screening against HIV-1.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.68-74
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• 2002

The tensile tests to identify the statistical tensile properties and the acoustic emission characteristics were conducted for STS304 stainless steel at $600^{\circ}C,\;700^{\circ}C$. From tensile tests performed by constant cross head speed controls with 1mm/min, rates at each elevated temperature, the scatters were observed in tensile strength, reduction of area, elongation and the acoustic emission parameters. The effect of temperature on the scatter of tensile behavior was larger at $700^{\circ}C$. The distributions of tensile properties was well followed in 3-parameter Weibull. The AE counts and energy of the $700^{\circ}C$ specimens were smaller than the $600^{\circ}C$.

• Journal of Ocean Engineering and Technology
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• v.17 no.1
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• pp.47-54
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• 2003

In this study, the residual stress and the acoustic emission Charactreistics from fatigue crack propagation were investigated, bused on the welded material of STS316L. The residual stress of welding locations could be evaluated by ultrasonic parameters, such as L$_{CR}$ wave velocity and L$_{CR}$ wave frequency； the residual stress between base metal and weld metal was evaluated. In the fatigue tests, three types of signals were observed, regardless of specimen condition, base metal, and weld metal. Based on NDE analysis of AE signals by the time-frequency analysis method, it should also be possible to evaluate, in real-time, the crack propagation and final fracture process, resulting from various damages and defects in welded structural members.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.383-392
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• 2013

Taguchi method is a technique widely used in industries to attain a reliable quality even under existence of various noise variables. Basically, it relies on the interactions between the controllable and the noise factors. Under insignificant interactions between the design parameters and noises, the effectiveness of Taguchi methodology will be doubtful. Furthermore, existence of strong interactions among controllable factors may undermine the power of Taguchi approach. An abundant crop may be expected by a well planned Taguchi approach. A well designed set of experiments is one of the important prerequisites for its successful result. For this, we must have a clear understanding on strengths and weaknesses of Taguchi methodology together with a sound knowledge on the applicable system. This study provides some insights on Taguchi approach based on two case examples of one successful and the other unsuccessful. Eventually, this research aims to facilitate deeper understanding and right application of Taguchi methodology in industries.

• Korean Journal of English Language and Linguistics
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• v.4 no.1
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• pp.33-60
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• 2004

This study was an attempt to present an appropriate way of interpreting L2 learners' linguistic behavior within Universal Grammar (UG) framework. Based on the Korean EFL adult learners' performance on the Subjacency violation sentences, the study suggested that the EFL learners are able to acquire subtle knowledge of target grammar and their linguistic behavior should be interpreted with the most recent version of UG theory, the Minimalist Program (MP) notion. The MP notion seems more plausible to accommodate incomplete L2 grammar while acknowledging UG-constrained interlanguage which the previous version, Principles and Parameters (P&P) approach, could not explain very well. The study observed no age-effects among the Korean EFL learners in their linguistic competence measured by the performance on the UG-constraint violation sentences. Having suggested that the MP notion can be a more reasonable tool to explain the EFL learners' linguistic behavior, the study introduced comprehensive hypotheses such as Constructionist Model (CM) and the Ontogeny Phylogeny Model (OPM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1989.06a
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• pp.83-86
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• 1989

Lead titanate thin films with a perovskite structure were successfully structure were successfully fabricated on titanium substrate by Chemical Vapour Deposition(CVD). Analyses of Auger Electron Spectroscopy(AES) and X-ray Photoelectron Spectroscopy (XPS) have been performed in order to find a chemical composition of lead titanate films. The analysis of chemical composition by AES and XPS was investigated for variations of deposition temperature and Ti(C$_2$H$_{5}$O)$_4$ fractions. The chemical composition of PbTiO$_3$by XPS analysis was almost constant regardless of deposition parameters and the comparison of chemical composition by AES and XPS was performed.d.

• Journal of Korean Society on Water Environment
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• v.25 no.3
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• pp.370-374
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• 2009

Adsorption characteristics of glass fibers, obtained from the spent lithium primary batteries recycling process, were investigated for the removal of Acid Red 27 dye from aqueous solution. The batch data clearly showed that increasing the initial sorptive concentration apparently enhanced the amount adsorbed and the uptake process followed the pseudo-second order rate model. The equilibrium adsorption data at different initial sorptive concentrations were fitted well to Freundlich and Langmuir adsorption isotherms. Moreover, the increase in temperature, favored the uptake of dye on this solid, indicated the process was endothermic in nature. Further, using the temperature dependence sorption data obtained at different temperatures was used to estimate various thermodynamic parameters.

• Publications of The Korean Astronomical Society
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• v.8 no.1
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• pp.1-15
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• 1993

We made a pyramidal horn antenna system for 21cm cosmic radio wave. The antenna system has a rectangular waveguide with $TE_{10}$ mode and a copper probe to detect the electromagnetic wave in waveguide. The parameters of the probe are obtained by experiments using two waveguides. Pyramidal horn antenna is designed to get a gain of 20dB. The size of the aperture of this horn is $94cm{\times}74cm$. The beam width of half power is about $14.7^{\circ}$ for the frequency of 1.4GHz. The horn is made of aluminum plate with a thickness of 2mm. The signal from horn and waveguide is amplified in a receiver system and is converted into DC in the detecter. The intensity of the signal is recorded on a chart recorder. We observed the sun using this simple radio telescope and obtained the brightness temperature of $2.2{\times}10^5K$, which indicates that the sun is quiet at 21cm.